For years, Ali al Naimi was the most important person in the world of oil: the former CEO of Saudi Aramco ascended to the post of Saudi oil minister in 1995, and over the past 21 years had the power to send the price of oil soaring or plunging with one word. To be sure, over the past two years it was mostly plunging because as is well-known, Saudi Arabia's policy ever since the 2014 Thanksgiving OPEC meeting in which Saudi Arabia broke off from the rest of the petroleum cartel to pursue its intention of putting US shale and high cost OPEC production out of business.

Then things unexpected, and dramatically, changed in April when Bloomberg published a detailed interview on the present and future of Saudi oil policy, which however took place not with al Naimi but with a young man few had heard of: Deputy Crown Prince Mohammed bin Salman, barely 30 years old, who just happens to be the favored son of Saudi Arabia's new King Salman who took control one year ago.

Suddenly not all was well in the top power echelons of oil, and less than three weeks later the FT wrote an extended profile of prince Mohammed bin Salman whom it dubbed "the unpredictable new voice of Saudi oil." This is what it said:

As the fallout from collapsed oil talks in Doha reverberates, Saudi Arabia’s Mohammed bin Salman has emerged as the unpredictable new voice of the kingdom’s energy policy.

The 30-year-old deputy crown prince and favoured son of King Salman was not even in the Qatari capital, where many of the world’s biggest oil producers had gathered in hopes of brokering the first global output deal in 15 years in an effort to arrest a prolonged price slide.

Still, his message echoed through the marble halls of the Sheraton: there would be no production freeze without Iran.

Around 3am on Sunday morning — just hours before the talks were due to begin — Prince Mohammed called the Saudi delegation, according to people briefed on the matter, and ordered them to come home. The Saudis ultimately remained, but the talks were effectively dead.

For oil watchers Doha was not so much about OPEC oil production, but about a huge power move that had just taken place in Saudi Arabia, as a result of which al Naimi had become irrelevant overnight.

The FT confirmed as much:

"the episode has left Ali al Naimi, the kingdom’s technocratic oil minister for the past 21 years, looking increasingly sidelined. While the Saudi royal family has always had the final say on oil policy, rarely has a member spoken so publicly — or freely — on its direction. Delegates from other countries had been assured Mr Naimi was there to deliver a deal. “Saudi Arabia’s oil policy is now firmly in the hands of Deputy Crown Prince Mohammed bin Salman,” said Sean Evers, managing partner of Gulf Intelligence in Doha."

This is all came to a stunning culmination moments ago, when Al Arabiya reported the shocking, if inevitable news, that Saudi Arabia has fired long-serving oil minister Ali al-Naimi, on Saturday. According to the WSJ, Naimi would be replaced with Khalid al-Falih, chairman of state oil company Aramco.

The royal decree, announced via state media, is part of a wider government reshuffle that includes a restructuring of the oil ministry, which has been renamed the Ministry of Energy, Industry and Mineral Resources, but the ultimate target is al Naimi who after 21 years at the helm of Saudi oil policy is gone, replaced effectively by bin Salman himself.

Who is al-Falih? Recall that shortly after the new Saudi King Salman bin Abdulaziz took power in 2015, he promptly shook up the nation’s energy industry on Wednesday, after he appointed Khalid al-Falih as the new chairman of Saudi Aramco and the country’s health minister (al Naimi had also been CEO of Aramco before he was elected to oil minister). Previously al-Falih was CEO of Aramco since 2009.

Even then the WSJ reported, that "the elevation of Mr. al-Falih from chief executive to chairman of the state-owned company raised questions about the tenure of the nation’s long-time oil minister, Ali al-Naimi, an influential figure in the world’s oil markets who has said he wants to retire soon." When Falih replaced al-Naimi as Aramco chairman, it was widely expected that he had become a contender to eventually take over the oil ministry.

What else do we know about al-Falih? Not much: he sits on the Board of Directors of U.S.-Saudi Arabian Business Council and also serves as a member of the JP Morgan International Council.

But ultimately this is not about the new oil minister: this is about Prince Mohammed taking full control over Saudi oil.

So the question everyone now wants answered is "what does this mean for oil?"

While nobody knows the answer, what is clear is that over the past 2 months, Prince Mohammed has had a far more hawkish outlook on oil prices. As noted above, it was Mohammed who effectively scuttled the Doha oil deal which was "this close" to reaching a conclusion before a last minute collapse as the crown prince intervened, overriding al Naimi's proposal.

Furthermore, as the FT reported at the time, "there were other signs that Saudi Arabia’s oil ministry was preparing for a deal. Between January and March the country held its oil output at around 10.2m barrels per day — a level consistent with the proposed freeze." Then a few weeks ago, Prince Mohammed once again poured cold water over any expectations that Saudi Arabia would permit higher oil prices when he said last week said "the country’s production could immediately rise to 11.5m b/d — if there was demand."

In other words, on the margin al Naimi's termination and Prince Mohammed's official ascent to the top of the Saudi oil chain of command is likely bearish in the short term, as Saudi Arabia reverts to its 2014 strategy of pushing oil prices low enough to put marginal producers out of business, a process that due to relentless hedging and generous banks, has taken way too long.

In summary, it is likely the slow fruition of Saudi plans to put high cost producers out of business, coupled with Saudi Arabia's own economic deterioration that forced the king to take this drastic measure.

As for the real impact on the price of oil, we will have to wait until Monday, although we can't wait to see what happens if Saudi Arabia's intentions are to push oil far lower once again to shock the complacent marginal producers and put them out of business once (or maybe twice) and for all, while algos and central banks continue to do everything in their power to push it higher.

Now that showdown will be worth the price of a barrel of oil or two.

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Also, in addition to replacing al Naimi, Saudi King Salman also appointed Ahmed al-Kholifey - currently an IMF executive director - Saudi Arabian Monetary Authority Governor, promoting him from vice governor and replacing Fahd al-Mubarak in charge of the kingdom's central bank. He also appointed Yasir al-Rumayyan, an adviser to the Royal Court and secretary general of the Public Investment Fund, and former SAMA governor Mohammed al-Jasser as advisers to the General Secretariat of the Cabinet.